Building Science
Kyle Schultz
November 16, 2022
Here’s the Scoop on the 2018 North Carolina Energy Conservation Code
- Taylor Fearrington
- September 25, 2018
- 6 min read
Hopefully by now you’re all aware that NC will be adopting a new building code on January 1st, 2019 (if not, pay extra close attention). This new code will be in place until 2024. As your energy experts, we’ve taken it upon ourselves to highlight the most notable changes to the new 2018 NCECC.
Here are the top 5 changes we think you’ll want to pay close attention to:
1. Soffitt Baffles
A long standing best practice is now explicitly called out as a requirement:
R4R402.2.3 Soffit Baffles
“For air-permeable insulation in vented attics, a baffle shall be installed adjacent to soffit vents. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.”
2. Climate Zone Specific Insulation & Fenestration Changes
There are minimal changes to all zones but most notable climate zone 3 will be required to have R-38 ceiling insulation and R-15 or R-13+2.5 wall insulation.
Table R402.1.2 Insulation and Fenestration Requirements by Component
| Climate Zone | Fenestration U-Factor | Skylight U-Factor | Glazed Fenestration SHGC | Ceiling R-Value | Wood Frame Wall R-Value | Mass Wall R-Value | Floor R-Value | Basement Wall R-Value | Slab R-Value & Depth | Crawl Space Wall R-Value |
|---|---|---|---|---|---|---|---|---|---|---|
| 3 | 0.35 | 0.55 | 0.30 | 38 or 30ci | 15 or 13+2.5 | 5/13 or 5/10ci | 19 | 5/13 | 0 | 5/13 |
| 4 | 0.35 | 0.55 | 0.30 | 38 or 30ci | 15 or 13+2.5 | 5/13 or 5/10ci | 19 | 10/15 | 10 | 10/15 |
| 5 | 0.35 | 0.55 | NR | 38 or 30ci | 19 or 13+5 or 15+3 | 13/17 or 13/12.5ci | 30 | 10/15 | 10 | 10/19 |
3. Building Thermal Envelope
Seams and joints of exterior house wrap and knee wall backing will be required to be sealed per the manufacturer’s instructions.
R402.4.1 #5
“Exterior house wrap material joints and seams are required to be sealed per the manufacturer’s instructions or, if house wrap joints are not sealed, seal exterior sheathing and exposed band joist joints including perimeter joints and edges of these materials.
Exemptions:
- Spray Foam in building thermal envelope wall systems
- Wall sheathing joints where wall sheathing is fully glued to framing"
R402.2.15 Attic Knee Walls
“… Joints shall be air sealed”
4. Duct Leakage
Duct leakage testing is still a mandatory item under the 2018 NCECC and the benchmark targets have moved to 5% total or 4% leakage to outside. The previous target had been set at 6% total.
R403.3.3.1 & R403.3.3.2
“Duct testing and duct leakage shall be verified by compliance with either section R403.3.3.1 (Total duct leakage shall be less than or equal to 5 cfm per 100 square feet) or R403.3.3.2 (Leakage to the outside shall be less than or equal to 4cfm per 100 square feet).”
403.3.3 Exemption #3
“Duct systems serving areas of 750 square feet or less shall not need to be required to be leak tested”
5. Energy Rating Index Compliance Alternative
The 2018 NCECC will now allow an Energy Rating Index (ERI) as a compliance pathway.
ERI - The New REScheck?
Read more about the ERI and how it may be a valuable tool for you in last month’s blog post!
Want more info?
This is only an abbreviated list of the most impactful changes. You can download a copy of the entire NCECC via the IECC website (Be sure to select 2018 under the “current adaptations” tab in the top left corner). Let us know if you still have questions, we’re happy to help!
Building Science
Jamie Hager
November 11, 2022
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